A standard sound pickup for a violin or other bow-type string instrument typically is a simple microphone secured to the bridge of the instrument. The analog output of this microphone is filtered to isolate the fundamental and the resultant output is fed to a synthesizer which builds on it the desired sound.
Such an arrangement is simply adapted from other monophonic sources. It cannot capture the glissando effect and cannot reproduce the harmonics of a string instrument. In addition this system is useless in the scientific analysis of play as might for instance be used for instructional purposes.